Starter Wiring - 3.0L Mercruiser

[stratmagic]

I just installed a brand new 3.0L GM base engine as a replacement for a 1982 2.5L mercruiser 120.

The old starter was dead so I took it to Autozone and bought another with the same part number which looked identical - until I started wiring. The old starter had two posts - "R" and "S" whereas the new starter has only one post.

Will I be able to wire this so that I can use this starter? Basically - I have two wires (purple/yellow that feeds the coils, and brown/white - which I have no idea what it is for.) If I put power to the purple/yellow the boat will start and run.

How do the "R" and "S" posts work? Does the solenoid send power to the "R" post only when the engine is cranking? Does the alternator then take over (possibly through the brown wire)? I think if I understand how it is supposed to work - I can probably figure a way around it.

I should also note that I have the service manual but I've yet to find a schematic that matches exactly (color, etc).

Any help would be greatly appreciated.
Doug

 

[Don S]

Re: Starter Wiring - 3.0L Mercruiser

Sounds like you may have gotten an automotive starter. You really need to get a marine starter. The marine starters are shielded against sparking and possibly igniting gas fumes in the bilge, should they be present.

That terminal puts full battery power to the coil (needed with points type ignition( when starting. Automotive hasn't used that terminal forever.

 

[Bondo]

Re: Starter Wiring - 3.0L Mercruiser

Ayuh,.....

You've got an Automotive Starter,...... You want to bring that back,+ Exchange it for the Right 1....
For Safety reasons, more so than the fact it Can't be wired properly on a Boat.....

The little Outside lug is powered with 12Vs while the starter is Engaged,......
And is Not powered when Running.....

The Inside little lug is the 1 that actually Engages the solenoid,+ starter.....

You should find all kinds of wiring diagrams in Here,...........